Re: cast to domain with default collation issue.

Please don’t top-post.

On Tuesday, May 24, 2022, jian he <jian.universality@gmail.com> wrote:

>
> Otherwise, all input expressions must have the same implicit collation
>> derivation or the default collation. If any non-default collation is
>> present, that is the result of the collation combination. Otherwise, the
>> result is the default collation.
>>
>
> I think the above quote part can be used to explain the  following
> examples.
>
>> CREATE TABLE test1 ( a text COLLATE "de_DE", b text COLLATE "es_ES", c
>> text );
>> SELECT a < 'foo' FROM test1;
>
> SELECT c < 'foo' FROM test1;
>
> But the *non-default* seems not that correct for me. Like a column if it does not mention anything, then the default value is null. So
> * create table test111( a tex*t) The default collation for column a is the same as the output of  *show lc_collate*.
>
> so there is no *non-default? *
>
>
I’m not following the point you are trying to make.  table111.a contributes
the default collation for any expression needing a collation implicitly
resolved.

David J.